Growth Curves for Children with X-linked Hypophosphatemia

J Clin Endocrinol Metab. 2020 Oct 1;105(10):3243-3249. doi: 10.1210/clinem/dgaa495.

Abstract

Context: We characterized linear growth in infants and children with X-linked hypophosphatemia (XLH).

Objective: Provide linear growth curves for children with XLH from birth to early adolescence.

Design: Data from 4 prior studies of XLH were pooled to construct growth curves. UX023-CL002 was an observational, retrospective chart review. Pretreatment data were collected from 3 interventional trials: two phase 2 trials (UX023-CL201, UX023-CL205) and a phase 3 trial (UX023-CL301).

Setting: Medical centers with expertise in treating XLH.

Patients: Children with XLH, 1-14 years of age.

Intervention: None.

Main outcome measure: Height-for-age linear growth curves, including values for the 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentiles for children with XLH compared to population norms.

Results: A total of 228 patients (132 girls, 96 boys) with 2381 height measurements were included. Nearly all subjects (> 99%) reported prior management with supplementation therapy. Compared to the Center for Disease Control and Prevention growth curves, boys at age 3 months, 6 months, 9 months, 1 year, and 2 years had median height percentiles of 46%, 37%, 26%, 18%, and 5%, respectively; for girls the median height percentiles were 52%, 37%, 25%, 18%, and 7%, respectively. Annual growth in children with XLH fell below that of healthy children near 1 year of age and progressively declined during early childhood, with all median height percentiles < 8% between 2 and 12 years old.

Conclusion: Children with XLH show decreased height gain by 1 year of age and remain below population norms thereafter. These data will help evaluate therapeutic interventions on linear growth for pediatric XLH.

Trial registration: ClinicalTrials.gov NCT02163577 NCT02750618 NCT02915705.

Keywords: FGF23; PHEX; X-linked hypophosphatemia; growth curve; rickets.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Body Height / physiology*
  • Child
  • Child Development / physiology*
  • Child, Preschool
  • Clinical Trials, Phase II as Topic
  • Clinical Trials, Phase III as Topic
  • Familial Hypophosphatemic Rickets / drug therapy
  • Familial Hypophosphatemic Rickets / physiopathology*
  • Female
  • Fibroblast Growth Factor-23
  • Genetic Diseases, X-Linked / drug therapy
  • Genetic Diseases, X-Linked / physiopathology*
  • Growth Charts*
  • Humans
  • Infant
  • Male
  • Phosphates / administration & dosage
  • Retrospective Studies
  • Treatment Outcome
  • Vitamin D / administration & dosage
  • Vitamin D / analogs & derivatives

Substances

  • FGF23 protein, human
  • Phosphates
  • Vitamin D
  • Fibroblast Growth Factor-23

Associated data

  • ClinicalTrials.gov/NCT02163577
  • ClinicalTrials.gov/NCT02750618
  • ClinicalTrials.gov/NCT02915705